After small mistake, travelled it’s said in exit lane (4,4)
I believe the answer is:
slip road
'exit lane' is the definition.
(a slip road is a road exiting a motorway)
'after small mistake travelled it's said' is the wordplay.
'after' is a charade indicator (letters next to each other).
'small mistake' becomes 'slip' (I've seen this before).
'travelled' becomes 'rode' (I've seen this before).
'it's said' shows a homophone (sound like).
'rode' sounds like 'road'.
'slip'+'road' is 'SLIP-ROAD'.
'in' is the link.
(Other definitions for slip road that I've seen before include "Motorway exit or entrance" , "way to access motorway" , "Motorway approach or exit" , "Joining lane" , "Motorway access point" .)